In reality, with 1/10 being unplayable and 10/10 being 'perfect'l, a 5/10 should mean average. But what it means in today's review culture is "fucking awful", with anything lower than that only being applied retroactively to games that are even worse and the 1 only going to games which only qualify because at some point they were released on a disc or cartridge (ET, Big Rigs 2). Even a 6 is considered unworthy, and you should only start playing games at a 7 and up.
So lots of merely 'good' games get 7's and you're forced to slot anything good in above that. It's getting to the point where if your favourite game doesn't get at least 9.5, then the reviewer was obviously paid off by the competition to make your preference look bad!
I no longer trust **/10 review scores. I might accept a grading because giving a game a C- or an A+ seems to be a more fair assessment of standalone quality instead of a comparitive, competitive score.
But even more so, I'd prefer a review be factual and informative, and let me make up my own mind about whether to play it. Kotaku does this well, merely listing what the reviewer liked or disliked, and why.